kernel.git/net/ipv6/ndisc.c, branch linux-6.5.y

net: change accept_ra_min_rtr_lft to affect all RA lifetimes

2023-10-10T20:02:55Z

commit 5027d54a9c30bc7ec808360378e2b4753f053f25 upstream. accept_ra_min_rtr_lft only considered the lifetime of the default route and discarded entire RAs accordingly. This change renames accept_ra_min_rtr_lft to accept_ra_min_lft, and applies the value to individual RA sections; in particular, router lifetime, PIO preferred lifetime, and RIO lifetime. If any of those lifetimes are lower than the configured value, the specific RA section is ignored. In order for the sysctl to be useful to Android, it should really apply to all lifetimes in the RA, since that is what determines the minimum frequency at which RAs must be processed by the kernel. Android uses hardware offloads to drop RAs for a fraction of the minimum of all lifetimes present in the RA (some networks have very frequent RAs (5s) with high lifetimes (2h)). Despite this, we have encountered networks that set the router lifetime to 30s which results in very frequent CPU wakeups. Instead of disabling IPv6 (and dropping IPv6 ethertype in the WiFi firmware) entirely on such networks, it seems better to ignore the misconfigured routers while still processing RAs from other IPv6 routers on the same network (i.e. to support IoT applications). The previous implementation dropped the entire RA based on router lifetime. This turned out to be hard to expand to the other lifetimes present in the RA in a consistent manner; dropping the entire RA based on RIO/PIO lifetimes would essentially require parsing the whole thing twice. Fixes: 1671bcfd76fd ("net: add sysctl accept_ra_min_rtr_lft") Cc: Lorenzo Colitti Signed-off-by: Patrick Rohr Reviewed-by: Maciej Żenczykowski Reviewed-by: David Ahern Link: https://lore.kernel.org/r/20230726230701.919212-1-prohr@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

net: add sysctl accept_ra_min_rtr_lft

2023-10-10T20:02:55Z

commit 1671bcfd76fdc0b9e65153cf759153083755fe4c upstream. This change adds a new sysctl accept_ra_min_rtr_lft to specify the minimum acceptable router lifetime in an RA. If the received RA router lifetime is less than the configured value (and not 0), the RA is ignored. This is useful for mobile devices, whose battery life can be impacted by networks that configure RAs with a short lifetime. On such networks, the device should never gain IPv6 provisioning and should attempt to drop RAs via hardware offload, if available. Signed-off-by: Patrick Rohr Cc: Maciej Żenczykowski Cc: Lorenzo Colitti Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

ipv6: adjust ndisc_is_useropt() to also return true for PIO

2023-08-09T22:36:12Z

The upcoming (and nearly finalized): https://datatracker.ietf.org/doc/draft-collink-6man-pio-pflag/ will update the IPv6 RA to include a new flag in the PIO field, which will serve as a hint to perform DHCPv6-PD. As we don't want DHCPv6 related logic inside the kernel, this piece of information needs to be exposed to userspace. The simplest option is to simply expose the entire PIO through the already existing mechanism. Even without this new flag, the already existing PIO R (router address) flag (from RFC6275) cannot AFAICT be handled entirely in kernel, and provides useful information that should be exposed to userspace (the router's global address, for use by Mobile IPv6). Also cc'ing stable@ for inclusion in LTS, as while technically this is not quite a bugfix, and instead more of a feature, it is absolutely trivial and the alternative is manually cherrypicking into all Android Common Kernel trees - and I know Greg will ask for it to be sent in via LTS instead... Cc: Jen Linkova Cc: Lorenzo Colitti Cc: David Ahern Cc: YOSHIFUJI Hideaki / 吉藤英明 Cc: stable@vger.kernel.org Signed-off-by: Maciej Żenczykowski Link: https://lore.kernel.org/r/20230807102533.1147559-1-maze@google.com Signed-off-by: Jakub Kicinski

neighbour: annotate lockless accesses to n->nud_state

2023-03-15T07:37:32Z

We have many lockless accesses to n->nud_state. Before adding another one in the following patch, add annotations to readers and writers. Signed-off-by: Eric Dumazet Reviewed-by: David Ahern Reviewed-by: Martin KaFai Lau Signed-off-by: Jakub Kicinski

ipv6: icmp6: add SKB_DROP_REASON_IPV6_NDISC_NS_OTHERHOST

2023-02-20T08:54:23Z

Hosts can often receive neighbour discovery messages that are not for them. Use a dedicated drop reason to make clear the packet is dropped for this normal case. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

ipv6: icmp6: add SKB_DROP_REASON_IPV6_NDISC_BAD_OPTIONS

2023-02-20T08:54:23Z

This is a generic drop reason for any error detected in ndisc_parse_options(). Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

ipv6: icmp6: add drop reason support to ndisc_redirect_rcv()

2023-02-20T08:54:23Z

Change ndisc_redirect_rcv() to return a drop reason. For the moment, return PKT_TOO_SMALL, NOT_SPECIFIED and values from icmpv6_notify(). More reasons are added later. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

ipv6: icmp6: add drop reason support to ndisc_router_discovery()

2023-02-20T08:54:23Z

Change ndisc_router_discovery() to return a drop reason. For the moment, return PKT_TOO_SMALL, NOT_SPECIFIED and SKB_CONSUMED. More reasons are added later. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

ipv6: icmp6: add drop reason support to ndisc_recv_rs()

2023-02-20T08:54:23Z

Change ndisc_recv_rs() to return a drop reason. For the moment, return PKT_TOO_SMALL, NOT_SPECIFIED or SKB_CONSUMED. More reasons are added later. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

ipv6: icmp6: add drop reason support to ndisc_recv_na()

2023-02-20T08:54:23Z

Change ndisc_recv_na() to return a drop reason. For the moment, return PKT_TOO_SMALL, NOT_SPECIFIED or SKB_CONSUMED. More reasons are added later. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller